Add the peanut butter, butter and Nutella into a microwave-safe container. Microwave on high for 30 seconds and stir to combine. Put the mixture in for another 15-30 seconds if it's not fully melted together yet, but be careful not to overheat and burn it. When it's melted, add the vanilla in and stir.

Pour the mixture over the chex cereal and stir until all the pieces are evenly coated. Put the powered sugar into a large ziplock bag, add the chocolate covered chex, seal the bag and shake until all the pieces are coated in powdered sugar.

Lay the pieces out to cool, and either serve or store in an airtight container.